NISCAIR Online Periodicals Repository Community: IJMS Vol.35 [2006]http://nopr.niscair.res.in/handle/123456789/1488
The Community's search engineSearch the Channelsearchhttp://nopr.niscair.res.in/simple-search
Oceanic mixed layer variations during the movement of cyclone along symmetric tracks in the Indian Oceanhttp://nopr.niscair.res.in/handle/123456789/30620
Title: Oceanic mixed layer variations during the movement of cyclone along symmetric tracks in the Indian Ocean
<br/>
<br/>Authors: Deo, A. A.; Ganer, D.W.; Salvekar, P. S.
<br/>
<br/>Abstract: <span style="mso-bidi-language:HI">The understanding of significant changes in the
oceanic mixed layer is important for dynamical prediction of tropical cyclone.
Present study aims at examining the variations in the upper ocean parameters
during the movement of tropical
<span style="mso-bidi-language:HI">cyclone in northern and southern Indian
Ocean, by applying 1½<i> </i>layer wind driven reduced gravity
ocean model. Different idealized tracks in the Bay of
Bengal and their mirror images in southern hemisphere are
considered, The model produced mixed layer depth, temperature and currents are
compared for northern and southern hemispheric cyclone cases. Also the effect
of latitude for westward moving cyclones in both the hemisphere is
investigated. For this, tracks in the Arabian Sea
<span style="mso-bidi-language:HI">and their counter parts in the southern hemisphere
are considered. The maximum cooling found in the wake of cyclone is of the
order of 3 - 4°C, which is comparable with earlier studies and observations.
This significant cooling can cause weakening of the storm. This can be useful
for prediction especially in the event of a cyclonic storm heading towards land
and likely to make land fall. Moreover it is also seen that the mixed layer is
cooled more on the right (left) of the storm track in northern (southern)
hemisphere. This cooling decreases for the storms translating along higher
latitudes implying the sensitivity of the latitudinal location of the storm.
</span></span></span>
<br/>
<br/>Page(s): 111-122Mon, 29 May 2006 22:58:59 GMTRemoval of polycyclic aromatic hydrocarbons from aqueous media by themarine fungus NIOCC # 312: involvement of lignin-degrading enzymes and exopolysaccharideshttp://nopr.niscair.res.in/handle/123456789/4169
Title: Removal of polycyclic aromatic hydrocarbons from aqueous media by themarine fungus NIOCC # 312: involvement of lignin-degrading enzymes and exopolysaccharides
<br/>
<br/>Authors: Raghukumar, Chandralata; Shailaja, M.S.; Parameswaran, P.S.; Singh, S.K.
<br/>
<br/>Abstract: The removal of polycyclic aromatic hydrocarbons from aqueous culture medium by the lignin-degrading marine fungus NIOCC # 312, obtained from decaying seagrass from a coral reef lagoon is reported here. We estimated the percentage of phenanthrene removed from the culture supernatant and the fungal biomass after 6 days. About 60-70% of phenanthrene, at a concentration of 12 mg l<sup>-1</sup> (12 ppm) was removed from the culture medium containing live or heat-killed fungus, as estimated by fluorescence spectroscopy method. Nuclear magnetic resonance spectra of the phenanthrene extracted from the fungal biomass revealed that in the heat-killed fungal biomass, the phenanthrene remained undegraded till day 6. On theother hand in the live fungal biomass, no phenanthrene was detected on day 6 suggesting that it was metabolized or transformed into non-aromatic fragments. We conclude that the disappearance of phenanthrene from the aqueous culture medium is due to its instant adsorption to the fungal biomass owing to the presence of the exopolymeric substance (EPS) around the fungal hyphae. The EPS produced by the fungus was partially characterized. We further hypothesize that phenanthrene thus adsorbed by the live fungal biomass was subsequently degraded by the lignin-degrading enzymes present in the cell wall and the EPS envelope. Thus, the heat-killed fungal biomass could be used only for adsorption of PAHs from contaminated sites whereas use of the live fungal biomass would result in degradation of PAHs.
<br/>
<br/>Page(s): 373-379Tue, 28 Nov 2006 22:58:59 GMTImpact of satellite derived wind in mesoscale simulation of Orissa super cyclonehttp://nopr.niscair.res.in/handle/123456789/4168
Title: Impact of satellite derived wind in mesoscale simulation of Orissa super cyclone
<br/>
<br/>Authors: Mandal, M.; Mohanty, U. C.; Das, A. K.
<br/>
<br/>Abstract: Prediction of track and intensity of tropical cyclones is one of the most challenging problems in numerical weather prediction (NWP). Providing reasonably accurate initial condition to tropical cyclone forecast models has always been a problem to numerical weather forecasters. Recent advancements in spatial resolution and radiometric sensitivity have significantly improved the accuracy and density of satellite derived wind. The objective of the present study is to examine the impact of satellite derived winds in improving model initial condition and hence in mesoscale simulation of cyclonic storm. In this study, PSU/NCAR mesoscale model MM5 is used to produce 5-day simulation of the super cyclone that crossed Orissa coast on 29 October 1999. Winds derived from QSCAT, SSM/I, MSMR and METEOSAT-5 satellites are used in preparation of high-resolution reanalysis (HRR) and improving model initial condition. The strength of the southwesterly wind (over ocean) converging to the storm is found to be stronger both in the HRR and improved model initial condition compared to that in the NCEP/NCAR reanalysis. The strength of the cyclonic vortex is also better represented in the HRR and improved model initial condition. Improvement in model initial condition has resulted in consistent and significant improvement (35% in average) in prediction of the track of the storm.
<br/>
<br/>Page(s): 161-173Mon, 29 May 2006 22:58:59 GMTMarine microbial eukaryotic diversity, with particular reference to fungi: Lessons from prokaryoteshttp://nopr.niscair.res.in/handle/123456789/1538
Title: Marine microbial eukaryotic diversity, with particular reference to fungi: Lessons from prokaryotes
<br/>
<br/>Authors: Raghukumar, Seshagiri
<br/>
<br/>Abstract: Novel molecular, analytical and culturing techniques have resulted in dramatic changes in our approaches towards marine eukaryotic diversity in recent years. This article reviews marine fungal diversity in the light of current knowledge, citing examples of how progress in understanding marine prokaryotes has often contributed to this new approach. Both ‘true fungi’ (termed mycenaean fungi in this review) and straminipilan fungi are considered. Molecular phylogenetic studies of prokaryotes has resulted in their redefinition as belonging to the Kingdoms Bacteria and Archaea. Likewise, major refinements have taken place in the phylogenetic classification of eukaryotes. In the case of fungi, it has now been realized that they are polyphyletic, belonging to the Kingdom Mycenae (Fungi), as well as the Kingdom Straminipila or Chromista. Although the total number of fungi on earth is estimated to be about 1.5 million, only a meagre number of obligate marine fungi , about 450 mycenaean and 50 straminipilan fungi have been described so far. It is likely that most of the true marine fungi have not yet been discovered. These are likely to have evolved between 1,500 million years ago (Ma) when fungi probably evolved in the sea and 900 Ma when they conquered land together with green plants. It now appears that most of the true marine fungi have not been cultured so far, similar to the ‘great plate count anomaly’ of bacteria. Thraustochytrids, which are abundant in the water column, but not easily culturable from that source is an example. Intelligent and novel culture methods might bring forth unusual and new marine fungi, as happened in the case of Pelagibacter ubique belonging to the SAR 11 group of bacteria. Molecular techniques might bring to light novel marine fungi, as is happening with bacteria. Such fungi may defy our conventional wisdom regarding these organisms in terms of morphology. Thus, several recent studies using 18S rRNA gene community profiles have discovered picoplanktonic marine fungi in the water column. Studies such as those on molecular diversity of eukaryotes in permanently anoxic habitats have also indicated that fungi may be abundant in exotic habitats and possess unusual physiology. A search for fungi in biodiversity-rich habitats, such as the coral reefs and the deep-sea, using a combination of molecular and novel culture methods is likely to reveal a fascinating diversity of marine fungi.
<br/>
<br/>Page(s): 388-398Tue, 28 Nov 2006 22:58:59 GMT